1. Technical Field
The present invention relates generally to an ignition apparatus for developing a spark firing voltage that is applied to one or more spark plugs of an internal combustion engine.
2. Discussion of the Background Art
Ignition coils are known for use in connection with an internal combustion engine such as an automobile engine, and which include a primary winding, a secondary winding, and a magnetic circuit. The magnetic circuit conventionally may comprise a cylindrical-shaped, central core extending along an axis, located radially inwardly of the primary and secondary windings and magnetically coupled thereto. The components are contained in a case formed of electrical insulating material, with an outer core or shield located outside of the case. One end of the secondary winding is conventionally configured to produce a relatively high voltage when a primary current through the primary winding is interrupted. In a common configuration, insulating resin or the like is introduced into the gap between the secondary winding and the case for insulating purposes. The high voltage end is coupled to a spark plug, as known, that is arranged to generate a discharge spark responsive to the high voltage. It is further known to provide relatively slender ignition coil configuration that is adapted for mounting directly above the spark plug—commonly referred to as a “pencil” coil.
U.S. Pat. No. 6,724,289 entitled “IGNITION APPARATUS HAVING FEATURE FOR SHIELDING THE HV TERMINAL” issued to Moga et al. disclose a pencil coil type ignition apparatus that includes an electrically conductive cup configured to engage and surround the high voltage terminal, thereby suppressing the electromagnetic field concentration at the high voltage terminal. Moga et al. further disclose a resistor between such cup and a spring (which connects to the spark plug). The resistor is provided for suppressing electromagnetic interference. In this regard, Moga et al. further disclose a second cup on the lower end of the resistor in order to provide, among other things, an interface to the spring. However, the arrangement in Moga et al. comprises multiple, individual pieces (i.e., the resistor and the second cup) in order to mate to the spring, increasing somewhat the complexity of the apparatus. In addition, a predetermined amount or volume of the insulating resin is used, which has a certain cost. It would be desirable to reduce this cost.
Accordingly, there is a need for an improved ignition apparatus that minimizes or eliminates one or more of the shortcomings as set forth above.